I've also seen traditionally published books in AMS ads. Just lately I saw Martha Wells' latest Murderbot book in the ad slider for some other science fiction book. I've also seen a Lee Child book at one point. Though it only seems to be the big names.
As for non-Americans not being able to see the also-boughts at Amazon.com, that certainly sucks for me. For though I'm in Germany and buy from Amazon.de, I browse at Amazon.com. Because I read mainly in English and the English language books at the German Amazon store often don't have also-boughts that are particularly relevant (e.g. every other book had Harry Potter and the Cursed Child in its also-boughts for a while) or maybe have none at all. So even if I don't buy at Amazon.com, seeing the also-boughts at Amazon.com help me find books to buy and read at my local Amazon store.
So in short, this sucks, whether as an author or a reader. And like Ann said, recommendation e-mails haven't been useful to me for a long time now. Because I don't want to buy East Friesian mysteries, no matter how often Amazon recommends them to me.